As multilayer film can greatly enhance magneto-optical (MO) effect, it has become a very promising structure used in Faraday rotator for optical isolator. The transmission characteristics, however, vary greatly in different order of the magneto-optical layers and dielectric layers. In this paper, different orders and structures, such as different material of gaps and the distance between the gaps and the stack of some structures, are discussed in order to have large rotation (45 degree), high transmittance and small size, all of which are very important in the made of Faraday rotator.